The goal of the proposed grant is to objectively test the effectiveness of intrathecal baclofen for spasticity. Patients with spasticity which significantly interferes with motor function or causes painful spasms will be screened with injections of intrathecal baclofen, and if they respond, a programmable drug pump will be implanted to give the medicine chronically. The dose levels needed to control painful spasms, clonus, and rigidity will be determined. Voluntary control, if present, will be tested in the Motor Control Laboratory. Once the optimal dosage has been selected, the patient will receive the drug continuously. Quantitative studies of motor function, as well as activities of daily living, will be assessed at regular intervals. The prospective study will provide information about the long-term efficacy, as well as the risks of the procedure. A secondary goal will be to relate decreases in rigidity, hyperactive reflexes and clonus to voluntary control. The basic question is: whether a reduction in the signs of spasticity necessarily means that voluntary control will improve? If voluntary control does improve, what signs are most predictive, and can these measurements be used to select patients who will respond best to treatment?